ELM95xxD
CMOS PWM step-up DC/DC converter
■External parts
To design DC/DC converter with ELM95 series, coil, diode, and capacitor are necessary.
(Refer to standard circuit configuration.)
1) Coil
When choosing choke coil, please select that whose core is not magnetically saturated, DC resistance is
low, and which has sufficient margin for rated current.
For ELM95 series, ELM recommends following coil.
• CM-5/CM-5N (Sumida Electric Co., Ltd.)
2) Diode
When choosing diode, please select that whose forward voltage is small, switching speed is high and which
has sufficient margin for rated current. For ELM95 series, ELM recommends schottoky diodes.
3) Capacitor
When choosing capacitor, please select that whose capacity is comparatively large and voltage limit is at
least three times larger than rated output voltage of used ELM95 series. For ELM95 series, ELM recom-
mends to use “Aluminum electrolytic capacitor”. When using capacitors such as “Tantalum capacitor” or
“Laminated ceramic capacitor”, there may be cases that few hundred hertz wave motion will happen in out-
put voltage wave form. Under such circumstances, ELM recommends connecting resistance (1.0Ω approx.)
to capacitor serially as following.
■Typical characteristics
• Vout=2.7V (ELM9527D)
Vout - Vin
100
(Top=25°C, L=220μH, D=MA721, C=47μF)
EFFICIENCY-Vin
- Vin
Efficiency,VRp-p
(Iout =1mA)
RIPPLE VOLTAGE-Vin
EFFICIENCY
EFFICIENCY
50
40
30
VRp-p
RIPPLE VOLTAGE
20
10
0
3
90
80
70
60
50
2
Iout =1mA
3mA
10mA
1
0
1
Vin (V)
2
0
1
Vin (V)
2
5- 4
RIPPLE VOLTAGE (mA)
VRp-p (mV)
EFFICIENCY (%)
Efficiency (%)
Vout (V)
ELM-TECH [ ELM Technology Corporation ]
